Near-end crosstalk (NEXT) in communication and data system connectors is an objectionable noise that results from capacitive and/or inductive coupling among the exposed, closely spaced, parallel conductors (contacts) within the jack and/or the mating plug. Crosstalk in a communication or data transmission system degrades the noise margin of the system, resulting in greater error rates in the information conveyed. Typical solutions for reducing near-end crosstalk apply crosstalk compensation signals to the affected jack conductors at particular locations. See, e.g., U.S. Pat. Nos. 5,997,358; 6,350,158; 7,153,168; and 7,367,849, and U.S. patent application Ser. No. 12/314,613, filed Dec. 12, 2008, all of which are incorporated by reference herein in their entireties.
The electrical length of a jack conductor—i.e., the distance between its point of contact with the inserted plug conductor and the point where compensation is applied—is a factor that affects the amount of compensation required. A shorter electrical length translates into more effective compensation up to higher frequencies, requiring less crosstalk compensation. The desired electrical length is less than 0.100 in., preferably closer to 0.060 in. However, the constraints of material and conventional jack geometry have kept the minimum electrical length achievable with traditional spring contact arrangements to greater than 0.130 in. In such arrangements, the jack spring contacts typically project away from the jack's printed circuit board (PCB) at a steep angle, resulting in high stress concentrations at each contact's rigid proximal anchoring point when deflected by an inserted connector plug. Any contact arrangement that would further shorten the electrical length must achieve the desired normal contact forces throughout the required contact deflection range without yielding or breaking due to excessive localized stresses. Solutions that attempt to achieve shorter electrical length involve rather complex arrangements, such as a movable second PCB, e.g., as disclosed in U.S. Pat. No. 7,153,168, or unusually long contacts that engage forward compensation contacts (see U.S. Pat. No. 6,350,158).
Crosstalk amplitude generally increases with higher data transmission rates. Network connectors attached to balanced twisted-pair copper cabling are now expected to meet at least Category 6A performance standards, which require crosstalk levels to be at least 34 dB below the level of the incoming signal at 500 MHz (ANSI/TIA-568-C.2). Demands for even higher data transmission rates are rendering some prior art solutions unsuitable for use in modern networks. A need thus has developed for a low-noise, simple and dependable connector for use in modern communications and data transmission systems.